Method for applying ultrafine phosphate conversion crystal coatings

Abstract

A method for providing phosphate conversion crystal coating, the method including the steps of: pre-treating a substrate by depositing metal oxide particles on the substrate; treating the substrate with a phosphate coating solution, resulting in the phosphate conversion crystal coating forming (crystallizing) on the substrate.

What is claimed is: 
     
       1. A method for providing phosphate conversion crystal coating, the method comprising the steps of:
 pretreating a substrate in a dry process by depositing metal oxide particles on said substrate; 
 treating said substrate with a phosphate coating solution, resulting in the phosphate conversion crystal coating forming on said substrate. 
 
     
     
       2. The method of  claim 1 , wherein crystallizing centers form at locations where said metal oxide particles were deposited prior to said treating of said substrate with said phosphate coating solution. 
     
     
       3. The method of  claim 1 , wherein said metal oxide particles are selected from the group comprising: CaO, ZnO, MnO, NiO and combinations thereof. 
     
     
       4. The method of  claim 1 , wherein said metal oxide particles are deposited on said substrate in a quantity of between 0.5 and 100 g/m2. 
     
     
       5. The method of  claim 1 , wherein a largest dimension of any of said metal oxide particles is less than 2 μm. 
     
     
       6. The method of  claim 1 , wherein said phosphate coating solution comprises oxides diluted in phosphoric acid, said oxides selected from the group comprising: Calcium Oxide, Zinc Oxide, Manganese Oxide and combinations thereof. 
     
     
       7. The method of  claim 1 , wherein said phosphate coating solution comprises phosphates selected from the group comprising: Zinc Phosphates, Manganese Phosphates, Calcium Phosphates and mixtures thereof. 
     
     
       8. The method of  claim 7 , wherein said phosphate coating solution comprising Zinc Phosphates reacts with said metal oxide particles when said phosphate coating solution is at a temperature of up to 35° C. 
     
     
       9. The method of  claim 7 , wherein said phosphate coating solution comprising Manganese Phosphates reacts with said metal oxide particles when said phosphate coating solution is at a temperature of up to 70° C. 
     
     
       10. The method of  claim 1 , wherein said phosphate coating solution has a pH range of between 2.2 and 2.7. 
     
     
       11. The method of  claim 1 , wherein said phosphate coating solution has a phosphate density of between 1.03 and 1.08 kg/l. 
     
     
       12. The method of  claim 1 , further comprising the steps of:
 pretreating said substrate with said phosphate coating formed thereon by depositing additional said metal oxide particles on said coated substrate; 
 treating said pretreated coated substrate with said phosphate coating solution, resulting in a second phosphate crystal coating layer forming on said coated substrate. 
 
     
     
       13. The method of  claim 12 , further comprising:
 repeating said pretreating and treating steps until a desired number of coating layers is formed on said substrate.